From the prior art, a control system for operating a motive installation (publication of the firm Sturdy Marine Division "Marine Digital Control System" masthead Sep. 21, 1988) is known. This concerns a motive installation having a port-side and a starboard-side engine which are operatively connected via a respective gearing with a port-side and a starboard-side propeller shaft. With each motive group are coordinated three adjusting devices (control means) for the throttle valve adjustment (throttle servo), for gear selection (gear shift servo) and for actuating an adjusting valve of a clutch (trolling valve servo). The control means enumerated are attached via an electric line connection to an electronic control mechanism (CPU). Another electric connection exists between the control posts and the control mechanism.
The ship's motive installation can be operated with the control system known already by the fact that from two possible operating mode bits, one mode bit is selected. In a first operating mode, one of the clutches (forward and astern movement) is completely engaged. The velocity of travel is produced by varying the engine speeds. In another mode of operation, one engine speed is maintained while the travel velocity of the ship is determined by the degree of slip of the clutches (trolling). Adjustable slip clutches for driving a ship forward and astern have been disclosed in DE-OS 21 20 639.
In another control system already known for operating a motive installation, a mode bit selector device is provided in which a specific manner of operation can be preselected. According to the manner of operation preselected, a certain function is associated with the control lever of the control post. When preselecting the travel mode bit (cruise control), the clutch for forward movement is engaged. The engine speed is varied with the control lever in order to adjust a specific travel speed. When the slow travel mode bit (troll mode) is preselected with the mode bit selector device, the function associated with the control lever is altered. As long as said mode bit is selected, the engine is operated at a specific, uniform speed. The travel speed is varied via the control lever in such a manner that the degree of slip of the respective clutch of the gearing is selected of a greater or lesser magnitude. The rate of revolution of the propeller shaft is thus varied via the degree of slip of the clutch. The known control system has at its disposal control electronics to which are attached an input and output unit, a display unit and control and sensor devices (see publication of the firm Twin Disc "Twin Disc Power Commander" masthead: 319 MEC 5M-1-88).
DE 39 07 841 A1 discloses exclusively a control apparatus for a ship's propulsion system which fundamentally coincides with the one above described. The control electronics consists of a main communication control mechanism and an auxiliary communication control mechanism. The port-side motive installation is controlled via the main control mechanism while the starboard-side motive installation is monitored by the auxiliary control mechanism. For this purpose, the port-side control levers of the control posts (main and secondary control posts) are attached to the main control mechanism while the control starboard-side control levers of the control posts (main and secondary control posts), respectively, have one electric connection to the auxiliary control mechanism. The main communication control mechanism is additionally connected with the auxiliary communication control mechanism via line connections. The control and sensor devices are each separately attached to the main control mechanism (on the port-side) and the auxiliary control mechanism (on the starboard-side). A mode selector device and a display unit are coordinated with each control lever.
The known control systems, which make it possible to operate a motive installation using control electronics, have the advantage that a precise regulation of specific nominal values (such as the engine speed and the propeller shaft speed) is possible. Despite the use of electronic parts, on the other hand, it has only been limitedly attained to facilitate to the user the operation of said systems. For the attachment of a control post two connecting lines are required which, when for instance using a total of six control posts, means that twelve line connections are always needed. To this must be added other line connections for interconnecting the control mechanism and attaching other functions (alarm, command keys for the post delivery and acceptance). It must further be borne in mind that the failure of the electronics does not always lead to the failure of both motive installations. The already known control systems in which a specific operating mode must be preselected require a certain measure of technical understanding for a faultless handling. On one hand, the operator not always has such a technical understanding to the desired extent and, on the other, it finally is another condition to have the ability to take into consideration other requirements and peculiarities when wiring such a ship's motive installation. For the above stated reasons, faulty conditions are not ruled out in the known control systems. This includes that the motive installation is not always operated as would be required and also possible in view of the given technical prerequisites.